<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>首页</title>

</head>
<body>
   <div id="left">
       <a href="/grade/grade.html" target="mainFrame">年级信息</a>
       <a href="/subject/list" target="mainFrame">课程信息</a>
       <a href="/student/list" target="mainFrame">学员信息</a>
   </div>
<div>
    <iframe name="mainFrame" frameborder="0" height="700px" width="100%" src="#">

    </iframe>
</div>
</body>
</html>